Abstract
Coal and gas outburst is a kind of complex dynamic disaster with short duration and strong explosiveness, and the modes and strength of the outburst are determined by the in situ stress, gas pressure, and physical and mechanical properties of the coal mass. In this paper, the status quo of research on the mechanism of coal and gas outburst in China is described from three aspects: the controlling effect of single factor, the controlling effect of multi-factor, and new understandings of the outburst mechanism in recent years. Firstly, controlling factors of coal and gas outburst are classified for an in-depth analysis of the main factors of the same type of disasters, and the research progress and new understandings of the mechanism of coal and gas outburst are systematically sorted out. Secondly, the influencing factors of the strength coal mass are analyzed, and the related issues of coal mass strength on coal and gas outburst disaster mechanism are discussed. The results show that the stages of incubation, occurrence, development, and stop on coal and gas outburst are affected by the coupling effects of in situ stress field, gas pressure field, and seepage field, and the coal strength becomes an important factor affecting outburst strength under the same in situ stress and gas pressure. Therefore, the scientific and reasonable improvement methods of such similar simulation experiment devices are proposed according to the existing experimental methods and devices, which is of great significance to provide ideas for the continuous transferring to deep mining and preventing coal and gas outburst in China in the future.
Highlights
Coal and gas outburst is a lump of typical coal and rock dynamic disaster in the process of coal mine production, which has become a key problem affecting the safety of coal production and causing serious casualties and property losses [1, 2]
In the practical explorations of the mechanism of coal and gas outburst, more and more scholars believe that coal and gas outbursts occur under the combined action of three main factors, namely, gas pressure, in situ stress, and physical and mechanical properties of coal mass [8, 9]
The increase of the tested coal size increases the possibility of the increase in the number of defect structures inside the coal mass, and this promotes the further initiation and evolution of new cracks due to the coupling effect between gas pressure and stress field, softening the coal further reducing the coal strength
Summary
Coal and gas outburst is a lump of typical coal and rock dynamic disaster in the process of coal mine production, which has become a key problem affecting the safety of coal production and causing serious casualties and property losses [1, 2]. Rough combining and analyzing related documents on the disaster mechanism of coal and gas outbursts under the coupling effect of multiple fields [16, 60], the in situ stress, gas pressure, and coal physical and mechanical properties have obvious differences in the various stages of coal and rock outbursts. Motion increment of the confined bulk calculated by using the motion mutation potential function It is believed [23] that the hypothesis of butterfly coal and gas outburst takes into account the uneven distribution of the ground stress caused by the excavation of the roadways in the working face and gives the stress field state and plastic zone boundary by using the implicit equation of the plastic zone boundary of circular roadway surrounding rock in nonisobaric stress field, which solves the quantitative interpretation of the risk indicators of coal and gas outburst risk indicators. Strength is one of the important parameters of the physical and mechanical properties of the coal mass, an essential index to predict the risk of coal and gas outbursts, and the strength value greatly affects the degree of damage of coal and gas outburst accidents [69]
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